It is known in the art to provide single-pass tillage implements which perform both shallow and deeper, primary tillage in a single pass. Typically, gangs of concavo-convex discs are utilized to perform the shallow tillage, while behind the discs sturdy shanks with various types of points are utilized to perform the deeper tillage. The discs are also typically used to cut and bury residue, to varying degrees. Several conventional machines, in an effort to have the soil in a fairly level condition by the time of the next planting season, use cooperating pairs of discs behind the tillage shanks to fill in furrows left by the shanks. Such discs typically are positioned to engage the two ridges produced by each advancing shank and to converge the ridges back into the shank's furrow whereby to create a raised berm that will settle down to a more level condition over the winter months before the next spring planting season. Some conventional machines also provide coulters at the front of the machine for residue-cutting purposes.
In one aspect the present invention is intended to provide an improved single-pass primary fall tillage machine which leaves the field in better condition for spring planting operations than has heretofore been possible. The machine not only cuts and partially buries residue left from harvesting operations, but also provides both deep and shallow tillage while leaving a smoother, more level field with smaller clod size.
The present invention provides a number of novel features, both individually and in combination. In one preferred embodiment, the machine has a group of laterally spaced, deep tillage shanks that are preceded by a transversely extending group of flat, residue-cutting coulters. Following the shanks is a group of soil-conditioning, concavo-convex discs that pulverize, level, and smooth the soil. Preferably, although not necessarily, the coulters are preceded by a gang of freely rotating residue wheels that engage and orient residue transversely for better severance by the coulters. Preferably, the residue wheels are each independently mounted, free-floating, and gravity-biased downwardly. The coulters are pressed downwardly as a group by a hydraulic hold-down circuit that allows the coulters to penetrate the soil to the extent necessary to achieve a firm backstop against which the coulters may cut the residue. The depth of penetration of the coulters is thus made independent of the depth of the tillage shanks, which are controlled by transport wheels on the main frame of the machine.
The conditioning discs at the rear of the machine are preferably arranged in at least two transversely extending, parallel rows with the discs of a trailing row being more closely spaced and greater in number than those of the front row. Preferably, the spacing of the discs in the trailing row is less than the spacing between the shanks, while the spacing of the discs in the front row is the same as the spacing between the shanks. While the discs in the front row are indexed with the shanks and are located to move soil from the shank ridge laterally back into the furrow behind the shank, the discs in the trailing row, being more closely spaced and angled in the opposite direction, serve the function of reducing clod size, mixing, and leveling the soil to provide a finish suitable for spring planting. Preferably, the discs of the conditioner are all individually mounted on transverse beams by generally C-shaped mounts, with at least the mounts of the discs in the trailing row having their open ends facing forwardly to minimize plugging. Best results are obtained when the discs of the trailing row are fluted.